'The Simple Life' star Nicole Richie finally confirms she's pregnant

The soon-to-be-formerThe Simple Life star confirmed to ABC News' Diane Sawyer that she and her boyfriend, Good Charlotte singer Joel Madden, are expecting their first child together, Reuters reported Wednesday.

"We are. I'm almost four months," Richie told Sawyer during an interview scheduled to air on Thursday's Good Morning America and Friday's 20/20, according to Reuters.

Richie's revelation that she's almost half-way through her pregnancy could help explain why the 25-year-old pleaded guilty last Friday in a Glendale, CA courthouse to charges stemming from a December arrest for driving under the influence of drugs and alcohol. She was sentenced to four days in jail and three years probation.

"I have a responsibility and it's something that I did wrong, and if I could personally apologize to every single person that has lost a loved one from drunk driving I would," Richie told Sawyer, according to Reuters. "Unfortunately I can't, but this is my way of paying my dues and taking responsibility and being an adult."

The start of her trial had originally been delayed twice at Richie's request until she entered the guilty plea, presumably because she wanted to get the prison stint over with before she was any further along with her pregnancy. While Richie was reportedly given no surrender date, she must complete her sentence by September 28.